3T MRI as a tool for noninvasive biomedical imaging of the body

有许多报告描述了3 T MRI在脑研究领域相对于1.5T MRI的优势，因为SNR的加倍效应改善了图像。另一方面，身体的3 T MRI具有挑战性;在空气-非空气界面丰富的身体中，更突出的磁化率伪影，由弱RF穿透和RF不均匀性引起的图像退化，四倍大的SAR等。然而，相信3 T MRI在临床身体成像中具有潜在的强大工具，我们用两种不同的策略处理了问题。一是找出3 T高信噪比MRI的优势区域，即常规1.5T MRI信噪比不足的区域。另一个问题是如何减小射频不均匀性和SAR增加等不利影响。经过两年的3 T体部MRI的使用，我们发现3 T MRI可以提供比1.5T MRI更好的图像。如3 T MRCP对肝管的详细显示优于1.5T的上级。3 T下HASTE图像的对比度更好。3 T可获得良好的子宫颈和卵巢图像。尽管肺内有空气，但在3 T下的肺实质薄层图像（短TE）显示了肺实质的详细结构。结合其他技术如呼吸触发和DTI，我们成功地在3 T上显示了肾脏的各向异性结构。虽然是初步的，这些结果表明，3 T MRI可以用来克服我们在1.5T MRI所遭受的困难。

There are numerous reports describing the advantages of 3T MRI over 1.5T MRI in the field of brain research because the doubling effect of SNR improve images. On the other hand, 3T MRI of the body had been challenging ; more prominent susceptibility artifact in the body where air-non air interface is abundant, image degradation caused by weak RF penetration and RF inhomogeneity, four-times greater SAR etc. However, believing that 3T MRI has potentially a powerful tool in clinical body imaging, we have dealt with problem with two different strategies. One is to find out the area where 3T MRI with high SNR is advantageous, i.e.the area conventional 1.5T MRI suffers from shortage of SNR. Another is to find out the ways to reduce the unfavorable effects such as RF inhomogeneity and increase in SAR. After two-years experience of 3T body MRI, we have found that 3T MRI could provide us with images much better than those obtained by 1.5T MRI. For example, MRCP at 3T is superior to 1.5T in the detailed depiction of hepatic duct. Contrast is better at HASTE images at 3T. We could obtain excellent images of the uterine cervix and ovary at 3T. Despite air in lung, thin-slice images of the lung parenchyma at 3T, with short TE, demonstrate detailed structure of the lung parenchyma. And with the combination of other techniques such as respiratory triggering and DTI, we have successfully visualized the anisotropic structure of the kidney much beautifully on 3T. Though preliminary, these results suggest that 3T MRI can be used to overcome the difficulties we have suffered at 1.5T MRI.